/*
 * Copyright 2002-2009 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.zb.orm.ext;

import java.beans.PropertyDescriptor;
import java.io.InputStream;
import java.io.Reader;
import java.io.Serializable;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;

import org.apache.commons.lang.ClassUtils;
import org.apache.commons.lang.SerializationUtils;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.beans.BeanUtils;
import org.springframework.beans.BeanWrapper;
import org.springframework.beans.NotWritablePropertyException;
import org.springframework.beans.PropertyAccessorFactory;
import org.springframework.beans.TypeMismatchException;
import org.springframework.dao.DataRetrievalFailureException;
import org.springframework.dao.InvalidDataAccessApiUsageException;
import org.springframework.jdbc.core.RowMapper;
import org.springframework.jdbc.support.JdbcUtils;
import org.springframework.jdbc.support.lob.LobHandler;
import org.springframework.util.Assert;

import com.zb.orm.meta.EntityColumnMetadata;
import com.zb.orm.meta.EntityMetadata;
import com.zb.util.JsonUtils;
import com.zb.util.ObjectUtils;

/**
 * {@link org.springframework.jdbc.core.RowMapper} implementation that converts
 * a row into a new instance of the specified mapped target class. The mapped
 * target class must be a top-level class and it must have a default or no-arg
 * constructor.
 *
 * <p>
 * Column values are mapped based on matching the column name as obtained from
 * result set metadata to public setters for the corresponding properties. The
 * names are matched either directly or by transforming a name separating the
 * parts with underscores to the same name using "camel" case.
 *
 * <p>
 * Mapping is provided for fields in the target class for many common types,
 * e.g.: String, boolean, Boolean, byte, Byte, short, Short, int, Integer, long,
 * Long, float, Float, double, Double, BigDecimal, <code>java.util.Date</code>,
 * etc.
 *
 * <p>
 * To facilitate mapping between columns and fields that don't have matching
 * names, try using column aliases in the SQL statement like
 * "select fname as first_name from customer".
 *
 * <p>
 * For 'null' values read from the databasem, we will attempt to call the
 * setter, but in the case of Java primitives, this causes a
 * TypeMismatchException. This class can be configured (using the
 * primitivesDefaultedForNullValue property) to trap this exception and use the
 * primitives default value. Be aware that if you use the values from the
 * generated bean to update the database the primitive value will have been set
 * to the primitive's default value instead of null.
 *
 * <p>
 * Please note that this class is designed to provide convenience rather than
 * high performance. For best performance consider using a custom RowMapper.
 *
 * @author Thomas Risberg
 * @author Juergen Hoeller
 * @since 2.5
 * @version $Id: $Id
 */
public class NRowMapper<T> implements RowMapper<T> {

    /** Logger available to subclasses */
    protected final Log logger = LogFactory.getLog(getClass());

    /** The class we are mapping to */
    private Class<T> mappedClass;

    /** Whether we're strictly validating */
    private boolean checkFullyPopulated = false;

    /** Whether we're defaulting primitives when mapping a null value */
    private boolean primitivesDefaultedForNullValue = false;

    /** Map of the fields we provide mapping for */
    private Map<String, PropertyDescriptor> mappedFields;

    /** Set of bean properties we provide mapping for */
    private Set<String> mappedProperties;

    /**
     * Create a new BeanPropertyRowMapper, accepting unpopulated properties in
     * the target bean.
     * <p>
     * Consider using the {@link #newInstance} factory method instead, which
     * allows for specifying the mapped type once only.
     *
     * @param mappedClass
     *            the class that each row should be mapped to
     * @param lobHandler
     *            a {@link org.springframework.jdbc.support.lob.LobHandler}
     *            object.
     * @since 0.0.7
     */
    public NRowMapper(LobHandler lobHandler, Class<T> mappedClass) {
        initialize(mappedClass);
        this.metadata = EntityMetadata.newInstance(mappedClass);
        this.lobHandler = lobHandler;
    }

    protected EntityMetadata<T> metadata;
    protected LobHandler lobHandler;

    /**
     * Set the class that each row should be mapped to.
     *
     * @param mappedClass
     *            a {@link java.lang.Class} object.
     * @since 0.0.7
     */
    public void setMappedClass(Class<T> mappedClass) {
        if (this.mappedClass == null) {
            initialize(mappedClass);
        } else {
            if (!this.mappedClass.equals(mappedClass)) {
                throw new InvalidDataAccessApiUsageException(
                        "The mapped class can not be reassigned to map to " + mappedClass + " since it is already providing mapping for " + this.mappedClass);
            }
        }
    }

    /**
     * Initialize the mapping metadata for the given class.
     *
     * @param mappedClass
     *            the mapped class.
     * @since 0.0.7
     */
    protected void initialize(Class<T> mappedClass) {
        this.mappedClass = mappedClass;
        this.mappedFields = new HashMap<String, PropertyDescriptor>();
        this.mappedProperties = new HashSet<String>();
        PropertyDescriptor[] pds = BeanUtils.getPropertyDescriptors(mappedClass);
        for (PropertyDescriptor pd : pds) {
            if (pd.getWriteMethod() != null) {
                this.mappedFields.put(pd.getName().toLowerCase(), pd);
                String underscoredName = underscoreName(pd.getName());
                if (!pd.getName().toLowerCase().equals(underscoredName)) {
                    this.mappedFields.put(underscoredName, pd);
                }
                this.mappedProperties.add(pd.getName());
            }
        }
    }

    /**
     * Convert a name in camelCase to an underscored name in lower case. Any
     * upper case letters are converted to lower case with a preceding
     * underscore.
     * 
     * @param name
     *            the string containing original name
     * @return the converted name
     */
    private String underscoreName(String name) {
        StringBuilder result = new StringBuilder();
        if (name != null && name.length() > 0) {
            result.append(name.substring(0, 1).toLowerCase());
            for (int i = 1; i < name.length(); i++) {
                String s = name.substring(i, i + 1);
                if (s.equals(s.toUpperCase())) {
                    result.append("_");
                    result.append(s.toLowerCase());
                } else {
                    result.append(s);
                }
            }
        }
        return result.toString();
    }

    /**
     * Get the class that we are mapping to.
     *
     * @return a {@link java.lang.Class} object.
     * @since 0.0.7
     */
    public final Class<T> getMappedClass() {
        return this.mappedClass;
    }

    /**
     * Set whether we're strictly validating that all bean properties have been
     * mapped from corresponding database fields.
     * <p>
     * Default is <code>false</code>, accepting unpopulated properties in the
     * target bean.
     *
     * @param checkFullyPopulated
     *            a boolean.
     * @since 0.0.7
     */
    public void setCheckFullyPopulated(boolean checkFullyPopulated) {
        this.checkFullyPopulated = checkFullyPopulated;
    }

    /**
     * Return whether we're strictly validating that all bean properties have
     * been mapped from corresponding database fields.
     *
     * @return a boolean.
     * @since 0.0.7
     */
    public boolean isCheckFullyPopulated() {
        return this.checkFullyPopulated;
    }

    /**
     * Set whether we're defaulting Java primitives in the case of mapping a
     * null value from corresponding database fields.
     * <p>
     * Default is <code>false</code>, throwing an exception when nulls are
     * mapped to Java primitives.
     *
     * @param primitivesDefaultedForNullValue
     *            a boolean.
     * @since 0.0.7
     */
    public void setPrimitivesDefaultedForNullValue(
            boolean primitivesDefaultedForNullValue) {
        this.primitivesDefaultedForNullValue = primitivesDefaultedForNullValue;
    }

    /**
     * Return whether we're defaulting Java primitives in the case of mapping a
     * null value from corresponding database fields.
     *
     * @return a boolean.
     * @since 0.0.7
     */
    public boolean isPrimitivesDefaultedForNullValue() {
        return primitivesDefaultedForNullValue;
    }

    private void processLob(T t, ResultSet rs, int i, EntityColumnMetadata md)
            throws SQLException {
        // TODO
        boolean isLazy = md.isLazy();
        if (!isLazy) {
            if (ClassUtils.isAssignable(md.getFieldType(), InputStream.class)) {
                ObjectUtils.setValue(t, md.getField(), this.lobHandler.getBlobAsBinaryStream(rs, i));
            } else if (ClassUtils.isAssignable(md.getFieldType(), Reader.class)) {
                ObjectUtils.setValue(t, md.getField(), this.lobHandler.getClobAsCharacterStream(rs, i));
            } else if (ClassUtils.isAssignable(md.getFieldType(), String.class)) {
                ObjectUtils.setValue(t, md.getField(), this.lobHandler.getClobAsString(rs, i));
            } else if (md.getFieldType().equals(byte[].class)) {
                ObjectUtils.setValue(t, md.getField(), this.lobHandler.getBlobAsBytes(rs, i));
            } else if (ClassUtils.isAssignable(md.getFieldType(), Serializable.class)) {
                InputStream tmpInput = this.lobHandler.getBlobAsBinaryStream(rs, i);
                Object foo = SerializationUtils.deserialize(tmpInput);
                ObjectUtils.setValue(t, md.getField(), foo);
            } else {
                Object foo = JsonUtils.fromJson(this.lobHandler.getClobAsString(rs, i), md.getFieldType());
                ObjectUtils.setValue(t, md.getField(), foo);
            }
        } else {
            throw new UnsupportedOperationException("//TODO lazy load");
        }
    }

    /**
     * {@inheritDoc}
     *
     * Extract the values for all columns in the current row.
     * <p>
     * Utilizes public setters and result set metadata.
     * 
     * @see java.sql.ResultSetMetaData
     */
    public T mapRow(ResultSet rs, int rowNumber) throws SQLException {
        Assert.state(this.mappedClass != null, "Mapped class was not specified");
        T mappedObject = BeanUtils.instantiate(this.mappedClass);
        BeanWrapper bw = PropertyAccessorFactory.forBeanPropertyAccess(mappedObject);
        initBeanWrapper(bw);

        ResultSetMetaData rsmd = rs.getMetaData();
        int columnCount = rsmd.getColumnCount();
        Set<String> populatedProperties = (isCheckFullyPopulated() ? new HashSet<String>() : null);

        for (int index = 1; index <= columnCount; index++) {
            String column = JdbcUtils.lookupColumnName(rsmd, index);

            // 处理大字段
            final EntityColumnMetadata columnMetadata = this.metadata.getColumnByField(column);
            if (columnMetadata.isLob()) {
                this.processLob(mappedObject, rs, index, columnMetadata);
                continue;
            }

            PropertyDescriptor pd = this.mappedFields.get(column.replaceAll(" ", "").toLowerCase());
            if (pd != null) {
                try {
                    Object value = getColumnValue(rs, index, pd);
                    if (logger.isDebugEnabled() && rowNumber == 0) {
                        logger.debug("Mapping column '" + column + "' to property '" + pd.getName() + "' of type " + pd.getPropertyType());
                    }
                    try {
                        bw.setPropertyValue(pd.getName(), value);
                    } catch (TypeMismatchException e) {
                        if (value == null && primitivesDefaultedForNullValue) {
                            logger.debug("Intercepted TypeMismatchException for row " + rowNumber
                                    + " and column '" + column
                                    + "' with value " + value
                                    + " when setting property '" + pd.getName()
                                    + "' of type " + pd.getPropertyType()
                                    + " on object: " + mappedObject);
                        } else {
                            throw e;
                        }
                    }
                    if (populatedProperties != null) {
                        populatedProperties.add(pd.getName());
                    }
                } catch (NotWritablePropertyException ex) {
                    throw new DataRetrievalFailureException("Unable to map column " + column + " to property " + pd.getName(), ex);
                }
            }
        }

        if (populatedProperties != null && !populatedProperties.equals(this.mappedProperties)) {
            throw new InvalidDataAccessApiUsageException(
                    "Given ResultSet does not contain all fields " + "necessary to populate object of class [" + this.mappedClass + "]: " + this.mappedProperties);
        }

        return mappedObject;
    }

    /**
     * Initialize the given BeanWrapper to be used for row mapping. To be called
     * for each row.
     * <p>
     * The default implementation is empty. Can be overridden in subclasses.
     *
     * @param bw
     *            the BeanWrapper to initialize
     * @since 0.0.7
     */
    protected void initBeanWrapper(BeanWrapper bw) {
    }

    /**
     * Retrieve a JDBC object value for the specified column.
     * <p>
     * The default implementation calls
     * {@link org.springframework.jdbc.support.JdbcUtils#getResultSetValue(java.sql.ResultSet, int, Class)}
     * . Subclasses may override this to check specific value types upfront, or
     * to post-process values return from <code>getResultSetValue</code>.
     *
     * @param rs
     *            is the ResultSet holding the data
     * @param index
     *            is the column index
     * @param pd
     *            the bean property that each result object is expected to match
     *            (or <code>null</code> if none specified)
     * @return the Object value
     * @throws java.sql.SQLException
     *             in case of extraction failure
     * @see org.springframework.jdbc.support.JdbcUtils#getResultSetValue(java.sql.ResultSet,
     *      int, Class)
     * @since 0.0.7
     */
    protected Object getColumnValue(ResultSet rs, int index, PropertyDescriptor pd) throws SQLException {
        return JdbcUtils.getResultSetValue(rs, index, pd.getPropertyType());
    }

    /**
     * <p>
     * newInstance.
     * </p>
     *
     * @param lobHandler
     *            a {@link org.springframework.jdbc.support.lob.LobHandler}
     *            object.
     * @param mappedClass
     *            a {@link java.lang.Class} object.
     * @param <T>
     *            a T object.
     * @return a {@link cn.yicha.commons.orm.jdbc.ext.NRowMapper} object.
     * @since 0.0.7
     */
    public static <T> NRowMapper<T> newInstance(LobHandler lobHandler,
            Class<T> mappedClass) {
        return new NRowMapper<T>(lobHandler, mappedClass);
    }

}
